DNA extraction from phytoseiid specimens preserved on a glass slide and molecular diagnostic

Abstract

This study focuses on the diagnostic of seven species of mite belonging to the family of Phytoseiidae; very important biocontrol agents of phytophagous mites. However, they are morphologically very similar and specific diagnostic is very difficult in fact using the traditional identification methods it is uncertain to identify a species especially when Authors use different characters, very often not stable in the time. In the 60’s M.me Athias-Henriot took into consideration the insemination apparatus that is considered a stable character in the time. According to her, the shape of this apparatus could be considered a major criterion for genus distinction. The aim of the present study is to establish, using molecular investigation, which theories is more correct. DNA were extracted from specimens preserved on a glass slide by three different methods, the organic (phenol-chloroform) Method, the Chelex® 100 extraction procedure and the DNA extraction by a DNneasy Tissue Kit. Phenol-chloroform extraction takes a relatively long period of time (5-6 days), but it produces consistent results. The modified Chelex technique involves less time and work (only 2 hours) and doesn’t require toxic organic solvents, the Qiagen kit did not allow extraction from mites mounted on glass slide 20 years ago. Molecular result (12S rRNA and RAPD-PCR) showed a clear difference between the species.